Electrical-wire insulator



(No Model.)

J. P. MARTIN.

,t ELEUTRIGAL WIRE INSULATOR. No. 286.937. Patented Oct. 16, 1883.

N PETERS. Phablilhngnphen Wuhingwn. DC.

and in such a manner as not only to form an at intermediate points to provide means for effectiveness of the coupling or insulator, and

To 62% whom, it may concern; i

IT ED STATES JOHN F. MARTIN, OF CHICAGO, ILLINOIS ELECTRICAL-WIRE. INSULATOR.

srizcIrIcATIoN forming part of Letters Patent No. 286,937, dated October 16, 1883. Application filed March 12, 1883. (No model.)

Be it known that I, JOHN F. IVIARTIN, a citizen of the United States, residing in Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Electrical-Wire Insulators, of which the following is a specification.

My invention relates to improvements in electrical-wire insulators composed of sheetpaper or woven fabric wound in concentric layers about itself in tubular form, and made in" sections coupled together in the desired length to form a separate chamber for each individual wire of an underground system.

The objects ofmy invention are to provide means/for coupling the sections conveniently air-tight joint, but to as effectually, if not more thoroughly, insulate the wire at the joints than is accomplished by the body of the insulator conveniently and effectively couplingthe sec tions of the insulator in such a manner that they may have a flexible, air-tight, and non-' conducting joint, whereby the direction of any section may be changed to a right or oblique angle without destroying in any degree the to provide a coupling adapted to attain the above-setforth objects, and at the same time to uniformly space off a series of the insulators bunched together, so that uniform air-spaces shall exist between eachadjacent insulator, so as to provide for a circulation of air and obviate induction as nearly as practicable. I attain these objects by devices illustrated in the accompanying drawings, in which- Figure 1 is a longitudinal section of an electric-wire conductor embodying my invention; Fig. 2, a similar view of a modification of the same, and Fig. 3 an end elevation of the tubes bunched.

Similar letters of reference indicate the same parts in the several figures of the drawings.

A A represent, respectively, opposing ,sections of an insulator composed either of sheetpaper or'-woven 'fabric wound in concentric layers about itself in tubular form, as more fully described in other appli cations filed herewith. These sections, as shown in Fig. 1, are coupled by means of a short tube, B, composed of woven fabric wound in concentric layers about itself, so that the inner diameter of the tube thereby formed corresponds with the eX- ternal diameter of theinsulator-sections, which are fitted tightly therein, preferablywith their opposing ends in contact with each other. Tubular coupling B should be of a length sufficientto insure a-rigidity of the joint, and may have intermediate layers of non-conducting compound formed by coating the fabric before forming the coupling, and, if deemed necessary, may be likewise coated internally, so as to cement it'to the insulator-sections.

To provide for coupling sections of the insulators which are arranged at differing angles-as, for instance, at street-corners, or where branching off fromthe main system to houses, &c., or up through the hollow posts supporting electric lights, alarm-boxes, &c.- I employ a tubular coupling, D, composed of rubber or other similarly-flexible material, united with the insulators in the same manner as those above described, except a necessary space between the ends of the sections when arranged at an abrupt angle to form the bend in the coupling.

The tubular rubber coupling may be protected from injury by moisture with any suitable wrapping; but such wrapping will not be necessary'in the system in which these couplings are designed to be employed, for the reason that means are employed for excluding moisture from the conduits, said system forming the subject-matter of another application.

By reference to Fig. 3 it will be seen that when the insulating-tubes are bunched, as they are when used in numbers in an underground system, the couplings equally serve to separate the tubes, so that uniform spaces exist between each of them, which spaces provide for a free circulation of dry air, affording a very effective insulating medium, and in this respect an important auxiliary. to the tubes.

Having described my invention, what I claim, and desire to secure by Letters Patent, 1s-

The combination, with a series of sectional tubular electric-wire insulators arranged par are separated and provided with air-spaces allel to each other, with the joints of the sevbetween each of them corresponding with the 10 eral insulators substantially in alignment, of thickness of the two opposing Walls of the a series of flexible couplings composed of short I coupling, substantially as described.

5 tubes, into which the end of each opposingsec- JOHN F. MARTIN.

tion is projected and tightly fitted, said coup- WVitnesses: V lings having surface-contact with each other V. XV. ELLIOTT,

throughout the series, so that the insulators JNO. G. ELLIOTT. 

